TM 9-787A Heavy Tractor M1 ALLIS-CHALMERS HD-1OW 1942 This tractor is of the crawler or track-laying type and may be used for either highway or cross country travel. Because of its relatively low center of gravity, the tractor can climb slopes as steep as 30 degrees, depending on the kind of footing available and the load being pulled.Power is supplied by a water-cooled, 4-cylinder, valve-in-head, 2-cycle Diesel engine.